1. Field of the Invention
The present invention generally relates to a rotation assembly and, more particularly, to a rotation assembly that may be coupled to a permanent magnet in order to form a rotor for a motor.
2. Description of the Related Art
Referring to FIG. 1, Taiwan Patent Publication No. 443671 discloses a conventional motor 8. The motor 8 includes a base 81, a stator 82 and a rotor 83. The base 81 is mounted with a shaft tube 811 and the stator 82 is coupled with the shaft tube 811. The rotor 83 includes a hub 831, a shaft 832 and a permanent magnet 833. The shaft 832 has an end formed on the hub 831 in an injection molding manner, as well as another end extending into and rotatably coupling with the shaft tube 811. The permanent magnet 833 is mounted on an inner face of the hub 831. With the above-described structure, the rotor 83 can start rotating when the stator 82 is electrified to generate an alternative magnetic field which interacts with the permanent magnet 833 of the rotor 83.
During manufacturing of the motor 8, the shaft 832 is firstly formed on the hub 831 in an integral injection manner, and the shaft 832 is then inserted into the shaft tube 811. However, the integrally-formed shaft 832 and hub 831 may not suit some conventional motors. Specifically, some conventional motors require a hub to be lastly assembled to a shaft only after the shaft is assembled to other members such as a base or stator.
Referring to FIG. 2, for example, a conventional rotation assembly 9 with non-integrally formed shaft and hub is shown. The rotation assembly 9 comprises a hub 91, a shaft 92 and a buckling member 93. The hub 91 has an assembly hole 911 having a plane face 912 and a protruding face 913 formed on an inner circumferential wall thereof. The shaft 92 has a fixing slot 921, a plane face 922 and a protruding face 923. The shaft 92 is inserted into the assembly hole 911 of the hub 91 in a way that the plane face 922 abuts with the plane face 912 in order to prevent the shaft 92 from rotating about the hub 91. In addition, the protruding face 923 also abuts with the protruding face 913. Thus, the buckling member 93 may prevent the shaft 92 from disengaging from the hub 91 after the buckling member 93 is inserted into the fixing slot 921.
The hub 91 of the rotation assembly 9 is generally made of a plastic material. However, the plastic material is elastic and tends to wear down easily. Therefore, when the rotation assembly 9 is coupled to a permanent magnet (not shown) to form a rotor for a motor (not shown), the shaft 92 is not efficiently prevented from rotating about the hub 91 merely relying on the abutting relation between the plane faces 912 and 922, especially during long-term rotation of the motor. Furthermore, a gap is formed between the plane faces 922 and 912 as the plane faces 922 and 912 tend to wear down easily after long-term rotation of the rotation assembly 9. As a result, loosing between the shaft 92 and the assembly hole 911 is caused, which not only can not efficiently prevent the shaft 92 from rotating about the hub 91, but also cause problems such as noises generated.